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Mark Clarke's blog

A few months ago I setup a new computer for my 73 year Mother and instead of installing Windows I decided to put Linux on the box. I wrestled with doing this for a while as I didn't want to have my Mom getting confused with a new interface. Previously windows had been installed on the old box. Another factor was that I am in Johannesburg while my Mom and Dad are in Durban.

Recently I have begun to experiment with the Google Web Toolkit. The GWT is an amazing framework that allows one to programme in pure java with the resulting application being cross-compiled into Javascript so that the entire application runs on the client browser with trips to the server occurring only when some middleware interaction takes place. Essentially your application becomes one javascript file.

Java Persistence API detached object gotchas

One of the issues to get your head around in both Hibernate and JPA is how to handle detached entities. In Hibernate one has to deal with the session object and in JPA it is called the persistence context.

While surfing the net I came across this interesting lay study on the number of IP addresses per capita. From the map it appears that South Africa does quiet well for this unit of measure. According to the map we have 1 IP address for between 1-10 people. This puts us in the same bracket as Europe and behind the US and OZ.

Spam is the ban of any system administrators life and many people have taken it for granted that they must simply live with a certain level of spam in their day-to-day lives. However this does not have to be the case. A combined spam filtering approach is what is needed to end the spam problem. We find that a combination of blacklists and greylisting is the magic bullet that kills spam dead.

Recently we had upgraade a db2 8.1 database running on Windows to db2 9 running on a Linux based server. From the IBM documentation it appeared that it was possible to upgrade the database and change platforms but it was quiet difficult to find out exactly how.

We recently setup opennms to monitor the status of a medium sized company with several Linux based servers. (opennms can monitor winows servers too.) The biggest challenge when setting up and configuring the system turned out not to be opennms itself, but rather snmp on servers.